At 10:32 AM 9/10/2006, you wrote:
Dave -
Sorry for the unwelcome and unintended publicity. . .
One item said between the lines is that you are accelerating at a constant
rate. And the downhill does not help you (much). Both, IMHO, are
'artifacts' of the CVT.
Sorry, this was not in my F500. This is my son on his 80cc Shifter
kart with 6 gears. Other comments below in context...
You will notice that the first part of the acceleration (on the slow part)
is precisely the same curve. But THEN it flattens out. And stops short.
And your rpms drop, signifying (probably, but we'll get to that) that you
lifted. So. If you had kept your foot to the floor, and done the same
distance, you SURELY would have achieved the same speed. Note that
acceleration is limited, and yours looks 'good', so the faster entry speed
helped you, but not as much as you thought.
You speed reading is spikey at lower speeds. Very 'up and down' at faster
sections. . . obiously lifts? Back to spikey: this indicates one of
The track was quite "bumpy" so could be driving the foot off the
gas. There was one section coming out of the last corner down to the
finish line that the karts had to go either right or left of the
center line else they would find themselves coming off a ski jump in
the middle of the track and being a few inches in the air with all four wheels.
several things - only one magnet (less important/likely at your speeds),
too high a measuring frequency (20k Hz should be fine), or "interference."
The speed wire runs near one of your loud wires - usually rpm or
temperature. Loud wires being antennae, that broadcast and are picked up by
other wires.
The only wire running along side wheel speed is the temp from the
water. RPM is on the other side of the kart.
I may change the measuring frequency next time we go out to see what
the difference in the mph trace looks like.
You rpm trace is quite spikey in sections. . . I strongly suspect
interference. Don't forget that your plug wires are very loud antennae.
I think it is more a combination of the track being quite bumpy in
those sections where the kart is being turned through T1-T2, T3 and
then the twisty section at the end from T6-T10
Outside of those sections the RPM trace looks smooth.
your g trace is too smooth. . . Though this could be road racing, I doubt
it (to get to 1.8 g's, you need sharp measurements). So. Either you are
measuring too low frequency, or you are smoothing too much (for my taste. .
.). I measure my main g's (lat and long) at 100 Hz, as they are vital in
autocrossing. My other accelerometers measure at twice this. . . < g >
Freq are at the AIM defaults. I may make changes based on your
recommendations to see what the traces look like.
Your egt's are also quite spikey. I am almost certain this is interference.
I had weird temp values until I moved all of my temp wires at least 6 inches
apart (small crosses don't seem to impact as much).
EGT is also on the opposite side of the Kart from the water temp.
You can reduce the need for shielding by separating your wires - though you
end up with a rat's nest of wires. You can also slip some braided metal
tubing over them (or aluminum foil. . .), though this MUST be grounded. I
have a sourse if you need it - 80 cents a foot?
chris eckles
atlanta
FMod 34
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